Calculating ATP Production Rates from Oxidative Phosphorylation and Glycolysis During Cell Activation

The balance between oxidative phosphorylation and glycolysis is shifted in a variety of cell types and tissues upon activation, proliferation, and differentiation. However, description of these metabolic switches has been mostly qualitative, particularly upon acute activation signals. We therefore applied a method to quantify rates of ATP production from oxygen consumption and extracellular acidification data obtained from the Seahorse XF Analyzer to study cell growth and activation. The method detects substantive changes in ATP utilization upon neuronal depolarization and T cell receptor activation that are not evident from steady-state ATP measurements. Furthermore, quantifying ATP utilization during pro-inflammatory macrophage activation reveals the hallmark increase in glycolysis is not merely a compensatory response to decreased oxidative phosphorylation upon LPS treatment. Rather, these changes occur independently, and the profound increases in glycolysis and total ATP utilization upon activation is largely driven by MyD88-linked signaling and independent of oxidative phosphorylation.